PARIS, Aug 18 (Reuters) - A seminar on Paris that Amherst College Professor Ronald Rosbottom gave a decade ago piqued the U.S. academic's curiosity about the Occupation, the four years when German troops held the French capital during World War Two.

Rosbottom began sifting through archives, pouring over memoirs and conducting interviews to uncover "how a familiar and beloved city became, even temporarily, threatening and uncanny." The result is "When Paris Went Dark: The City of Light Under German Occupation 1940-1944" published by Little, Brown.

On the eve of the 70th anniversary of the liberation of Paris, Reuters spoke to the author about this still thorny period of French history.

Q: You call yourself a storyteller, not a historian.

A: I came up with the term 'tactile history'. I wanted to give a sense of what it felt like to get up every morning either as a German or a Parisian and have to worry about feeding your family or going to work or saying the wrong thing or what to do if your Jewish neighbor asked a favour of you. I wanted to write a group of narratives where people expressed what it was like to live on a daily basis.

Q: It's visceral. You talk about the cold, the noise, the inhabitants' acute sense of hearing. Parisians could tell if you were German or French from the sound of your footsteps - boots versus wooden-soled shoes due to the scarcity of rubber.

A: Or if they heard a car engine ... because most of the cars were German-controlled, they immediately had to evaluate everything. Can you imagine having a curfew in the middle of the summer at say 8 or 9 o'clock, and you had to be home and it's still bright? People's sense of space narrowed during this time.

If you were a Jew the whole algorithm changes. You can't shop except certain hours or you can't have bicycles, you can't have telephones, the rules kept changing. Every six months there was a new regulation. If you weren't Jewish, you still had to worry about food stamps and when the shops would be open and is the Metro running on time. For four years there was no predictability even for non-Jews and I think that must have an enormous psychological effect on Parisian well-being.

Q: You also explore how the Germans felt in this city that many of them loved and their anxiety about being hated.

A: I got more and more interested in that story. They felt sorry for themselves, some of them. There was a naivete on the part of the Germans that somehow, since they were being gentlemen at first, except to Jews, why weren't people being nice back to them? There was a joke about a soldier going into a shop and saying to the lady 'I'm so happy to be here, this is the most beautiful city, you're so lucky to live here' and she says, "You should have seen it before you came."

Q: The Occupation brings up a lot of uncomfortable questions over the extent of collaboration. It took historians from outside France to have a closer look at this period.

A: It was (American) Robert Paxton who really blew the cover off by in effect saying Vichy was a quite predictable response because there had been a very strong right-wing, monarchist, pro-military, religious strain among many Frenchmen.

Once the cover came off the kind of collective agreement that 'we're not going to talk much about the Occupation', then the French really dug into it and they've written brilliant histories on this, too. With a new generation, maybe two, people are asking more and more questions. It was a slow process - this openness is only a decade old.

Of course, another reason people didn't want to bring this up was because of the French culpability in the rounding up of Jews. Ninety percent of the Jews arrested were arrested by French police. And 4,000 children were killed, were sent to Auschwitz. It's not just a question of who is right or wrong politically. It was a question of participating in one of the 20th century's worst crimes.

Q: You talk about the difficulty of defining what is resistance and what is collaboration. It's not black or white.

A: The first question is 'should I resist and if so, how?' Is resisting, for instance, a concierge sees some kids outside have written 'Vive DeGaulle' and should she erase that? Or should she leave it even though it's her job to keep the building clean? Little, tiny, everyday ethical decisions had to be made.

It was so complicated. 'Do I smile at a soldier passing by who smiles at me? Do I smile when I serve him a cup of coffee?' And then the bigger ones were 'do I sneak around at night and write on walls, do I pass out tracts? Should I accommodate and just wait until the war's over or collaborate and maybe prosper?'

This is what upset people when I was talking to them - if you haven't lived through this you don't know how many little ethical decisions you're having to make every day that may affect you and your family. (Reporting By Alexandria Sage; Editing by Andrew Heavens)